Mechanisms of surface wave plasma excitation and energy transfer from electromagnetic wave.

点击翻译按钮获取中文摘要

Phenomena related to the surface wave plasma excitation have been found by Langmuir probe. They will be summarized as follow;1. Axial density profiles became moderate with the pressure decreasing.2. At the pressure lower than 50 mTorr, the dip appears on the probe characteristic curves detected around 1-2 cm from the quartz plate. Decreasing the probe bias voltage lower than -80 V with respect to the ground, the dip disappeared. This means that the dip is created by hot electrons which is produced by a certain electron acceleration mechanism.3. Measurement by the probe with a metal surface only on its one side showed that the electron flux with high energy flew down from quartz plate to the bottom of the discharge chamber.4. The signals picked up by dipole antenna which is set up at 5 mm from the quartz plate are frequency analyzed. As a result, three frequency spectra such as fィイD20ィエD2 = 2.45 GHz, fィイD21ィエD2 = 10 MHz and fィイD22ィエD2 = fィイD21ィエD2 + fィイD20ィエD2 are observed. Apparently fィイD20ィエD2 is the microwave frequency, while fィイD21ィエD2 corresponds to ion plasma frequency. Therefore, these phenomena is considered to be excited by so-called "parametric instability".In conclusion, Langmuir wave excited by parametric instability may transfer the energy to the electrons through a nonlinear phenomena such as Landau damping and then hot electrons produced here may contribute to the plasma production even though the electron collision with neutral particles were not so frequent because of a low filling pressure.